If you have a fully ionised plasma, the electron-neutral collision frequency will tend to zero (as you don't have any neutrals anymore) and the collisionless skin depth d should be taken: d = c/wpe

with c as the speed of light and wpe the electron plasma frequency.

It is the same as the Debye length?

no, it is not, altough the equations look quite similar

I should need to add to the excel table (I have the frequency there for ions and electrons). In order to not make errors, I suppose the Wpe cames in radians not hertz

Data Useful formula and excel tables for plasma physics V08

That is the skin depth as you said for equilibrium plasma but when introduced a high power electromagnetic field things changes dramatically as long as there is not enough space charge to shield the electromagnetics

no, not equilibrium plasma - fully ionised plasma. The main thing that matters for the skin depth is the collision frequency between electrons and neutral. I can recommend the book Plasma Physics by A. Piehl on that matter.

You can find all theory and formulas on the subject of interest written in accessible manner in the book Raizer Yuri. Gas discharge physics. Springer-Verlag, 1991. Particularly one can easily find formula (or formulas) required to calculate the value placed separatly on page 436 in chapter Formulas at the end of the book.

Hannes, in your book it is concentrated all data at 11.3 chapter, only 3 pages

Thank you Mikhail, I will print the formulas. It is a pity it is in CGS with its horrible Ergs

I should add:

Principles of Plasma Discharges and Materials Processing, Michael A. Lieberman

Also: Radio-Frequency Plasmas by Pascal Chabert

It can understand now why the Plasma Physics excel table has so many downloads

The problem is with the conductivity because has an imaginary part and so everybody avoids it by using approximations

I think the skin depth can depend on frequency but it does not say that it has an imaginary part as long as it can be measured in meters.

It may be easy to measure using capacitive coupling as long as if taking in account plasma is like a metal, the capacity is C1+AEo/s (s is skin depth and E0 is the permittivity of vacuum: 8.85e-12, A is the capacitor plates area) and C1 is the capacity of the vacuum container between plasma and metal sheet

The resistance can be measured taking into account the damping factor of the injected RF.

In the inductive coupling, the main parameter should be the plasma inductance, resistance, and the coupling coefficient (between 0 and 1) between outside coil and plasma coil. It can be measured using two structures: a tokamak-like to measure as the plasma would be "coil in short circuit" and the second one a cylinder, where it can be measured as the plasma would be as an "open coil"

It is a way to obtain electrical characteristics of a "black box" plasma in order to calculate the more effective system to heat and ionize it

The question seems to be rather complex regarding the dependence of the skin depth on several electron-plasma parameters! As a simple guideline, the plasma temperature usually peaks at the classical skin depth for a given (moderate) frequency. Then, as the frequency increases, the skin depth decreases, while the magnitude of the electric field and the ability for power deposit within the normal skin depth increases. In a fully ionized plasma, the skin depth likely becomes fully anomalous.

I have uploaded a Paper about a new magnetic sensor that can be used to measure the magnetic skin depth at high frequency. It would be interesting use it inside a plasma to see if the skin depth is higher for magnetic induction